Conventionally, a machine-tool such as machining center, etc. is provided with a plurality of work pallets in a pallet magazine, and performs machining of works by transferring and fixing the work pallet to the table of the machine-tool.
It is often the case that a hydraulically driven positioning mechanism and a clamping mechanism are provided on the work pallet, and a hydraulic coupling mechanism for supplying hydraulic pressure in a plurality of lines from the table side to the work pallet is also provided in many cases. Here, the table is rotatable around a vertical axis by its dividing function, and this makes it possible, in the case of a horizontal-type machining center, for example, to perform machining on four faces of the work in the case where the work is fixed on a horizontal plane, and on three faces of the work in the case where the work is fixed on a vertical plane, by rotating the table.
However, to machine the remaining one face other than the fixed faces on the work pallet side, it is necessary to once remove the work from the work pallet, change the orientation of fixing of the work and then fix the work on the work pallet again, and this presents a problem of poor machining efficiency. Under such circumstances, proposal is made of a work pallet comprising a base body to be fixed to the table, and a work setting face forming body, this work setting face forming body being constructed rotatably by electric motor around a horizontal axis.
In the case of a work pallet comprising a base body and a work setting face forming body, wherein the work setting face forming body is driven to turn by electric motor, as described above, it is necessary to feed electric power to the work pallet which is provided with an electric motor, and this not only involves complication of the power feed lines but also requires a complicated control system for controlling the motor to make the work pallet turn at prescribed angle (by 90° each time, for example), presenting a problem of high work pallet manufacturing cost.
The objective of the present invention is to provide a work pallet of simple structure and capable of machining five faces of the work by turning the work around a rotational axis.